Can’t exclude benefit
Thomas Jeerakathil, MD, a professor at the University of Alberta and Northern Stroke Lead, Cardiovascular and Stroke Strategic Clinical Network, Alberta Health Services, Edmonton, commented on the study for this news organization. Like the authors, he said, “I don’t consider this study to definitively exclude the benefit of EC/IC bypass. More studies are required.”
Dr. Jeerakathil would like to see a study of a higher-risk group based on both clinical and hemodynamic blood flow criteria. In the current study, he said, “The trial group overall may not have been at high enough stroke risk to justify the up-front risks of the EC-IC bypass procedure.”
In addition, “The analysis method of Cox proportional hazards regression for the primary outcome did not fit the data when the perioperative period was combined with the period beyond 30 days,” he noted. “The researchers were open about this and did pivot and included a post hoc relative risk-based analysis, but the validity of their primary analysis is questionable.”
Furthermore, the study was “somewhat underpowered with a relatively small sample size and had the potential to miss clinically significant differences between groups,” he said. “It would be good to see a longer follow-up period of at least 5 years added to this trial and used in future trials, rather than 2 years.”
“Lastly,” he said, “it’s difficult to ignore the reduction in recurrent stroke events over the 30-day to 2-year time period associated with EC-IC bypass (from 10.3% down to 2%). This reduction alone shows the procedure has some potential to prevent stroke and would argue for more trials.”
EC-IC could be considered for patients who have failed other medical therapies and have more substantial evidence of compromised blood flow to the brain than those in the CMOSS trial, he noted, as many of these patients have few other options. “In our center and many other centers, the approach to EC-IC bypass is probably much more selective than used in the trial.”
Dr. Jeerakathil concluded, “Clinicians should be cautious about offering the procedure to patients with just mildly delayed blood flow in the hemisphere affected by the occluded artery and those who have not yet failed maximal medical therapy.”
But Seemant Chaturvedi, MD, and J. Marc Simard, MD, PhD, both of the University of Maryland, Baltimore, are not as optimistic about the potential for EC-IC.
Writing in a related editorial, they conclude that the results with EC-IC bypass surgery in randomized trials “remain unimpressive. Until a better understanding of the unique hemodynamic features of the brain is achieved, it will be difficult for neurosurgeons to continue offering this procedure to patients with ICA or MCA occlusion. Intensive, multifaceted medical therapy remains the first-line treatment for [these] patients.”
The study was supported by a research grant from the National Health Commission of the People’s Republic of China. Dr. Jiao, Dr. Jeerakathil, Dr. Chaturvedi, and Dr. Simard reported no conflicts of interest.
A version of this article first appeared on Medscape.com.